Ester-C's patent has been sold a select few manufactures and this being one of them. This is an outstanding product and have had excellent results with this manufacture. Also I like the fact that this company and brand is GMP certified as well. Highly recommended.

I work in human services and come in contact with numerous people within a day. I usually get sick at least 2-3 times within the winter. I bought a store brand vitamin C before the "cold season" began and thought I was covered. I got sick shortly after (in December) and a friend recommended this brand of vitamin C. I have not changed anything else and I have not gotten sick since the beginning of December! (it is now middle of March) Also, I have acid reflux and other vitamin C products usually don't agree with me, but I have never had a problem with Ester C. Great product- no wonder it's patented!